The overall goals of the Behavioral Rodent Assessment and Biostatistical Core Subprojects 0002 and 0003 are to provide a unified methodology to assess behavior for the rodent projects in this Program Subprojects 0002 and 0003 and to utilize common statistical methodology throughout our program of research Subprojects 0001, 0002, 0003, will do the following: a. Establish and implement a methodology to determine whether aged rats under study can be classified as pre-senescent or senescent. B. Develop normative values for parameters to describe the rhythm of rest/activity of rats in the three groups being studied, i.e., young, pre- senescent old and senescent old rats. These values will be used to assess whether an individual rat under study is representative of rats for its particular age group. This is in a sense a quality control procedure and will be part of the extensive evaluation we will perform of each and every rat. c. Establish the effect on sleep produced by the experimental handling and procedures we plan to use. We will establish this for both the experimental (sleep deprived) animal and for handled control animals. Studies will be done in rats of each of the age groups, i.e., young, pre- senescent and senescent, and for each of the durations of sleep deprivations we plan to use, i.e., 6, 12 and 24 hours. d. Provide support for the animal protocols in subproject 0003 behavioral assessment, tissue sampling, sleep recording, ICV injections and microinjections into the rostral basal forebrain. 3. Provide biostatistical support for each of the three projects. This will involve data processing, development of statistical models and interpretation of data.